The deaths of Kate Spade and Anthony Bourdain, both of whom died by suicide this past week, were not simply pop culture tragedies. They were the latest markers of an intractable public health crisis that has been unfolding in slow motion for a ­generation.

Treatment for chronic depression and anxiety — often the precursors to suicide — has never been more available and more widespread. Yet the Centers for Disease Control and Prevention last week reported a steady, stubborn rise in the national suicide rate, up 25 percent since 1999.

The rates have been climbing each year across most age and ethnic groups. Suicide is now the 10th leading cause of death in the U.S. Nearly 45,000 Americans killed themselves in 2016, twice the number who died by homicide.

After decades of research, effective prevention strategies are lacking. It remains difficult, perhaps impossible, to predict who will die by suicide, and the phenomenon is extremely difficult for researchers to study.

One of the few proven interventions is unpalatable to wide swaths of the U.S. public: reduced access to guns. The CDC report found that the states where rates rose most sharply were those, like Montana and Oklahoma, where gun ownership is more common.

It is predominantly men who use guns to kill themselves, and men are much less likely to seek help than women.

New York Daily News

A memorial honoring Anthony Bourdain in front of his former restaurant, Brasserie Les Halles, in Manhattan.

The escalating suicide rate is a profound indictment of the country’s mental health system. Most people who kill themselves have identifiable psychiatric symptoms, even if they never get an official ­diagnosis.

The rise in suicide rates has coincided over the past two decades with a vast increase in the number of Americans given a diagnosis of depression or anxiety, and treated with medication.

Antidepressant use is way up

The number of people taking an open-ended prescription for an antidepressant is at a historic high. More than 15 million Americans have been on the drugs for more than five years, a rate that has more than tripled since 2000.

But if treatment is so helpful, why hasn’t its expansion halted or reversed suicide trends? “This is the question I’ve been wrestling with: Are we somehow causing increased morbidity and mortality with our interventions?” said Dr. Thomas Insel, former director of the National Institute of Mental Health and now president of Mindstrong Health, which makes technology to monitor people with mental health problems.

“I don’t think so,” Insel continued. “I think the increase in demand for the services is so huge that the expansion of treatment thus far is simply insufficient to make a dent in what is a huge social change.”

But in this country, many of those who die by suicide have received little or no professional help. Indeed, they rarely tell anyone beforehand of their plan — when there is one. Often the act is impulsive.

According to Matthew Nock, a Harvard professor of psychology, the wide majority of people who die by suicide “explicitly deny suicidal thoughts or intentions in their last communications before dying.”

Andrew Spade, Kate Spade’s husband, said she had seemed fine when he’d talked to her just before her suicide. Bourdain was filming one of his clever, humorous shows in Alsace, France, when his body was discovered.

The rise of suicide turns a dark mirror on modern American society: its racing, fractured culture; its flimsy mental health system; and the desperation of so many individual souls, hidden behind the waves of smiling social media photos and cute emoticons.

“In contrast to homicide and traffic safety and other public health issues, there’s no one accountable, no one whose job it is to prevent these deaths — no one who gets fired if these numbers go from 45,000 to 50,000,” Insel said. “It’s shameful. We would never tolerate that in other areas of public health and medicine.”